Patch Testing Pearls

[Translated article] Allergic Contact Dermatitis to Topical Ophthalmic Drugs: Review of Frequently Used Allergens in Spain

Allergic contact dermatitis induced by the use of ophthalmic topical drugs is one of the most common causes of eyelid dermatitis. The introduction of new formulations, both of active ingredients and excipients, and the lack of marketing in some of them, makes patch testing in patients whose source of contact are topical ophthalmic drugs truly challenging. Across this manuscript, most, if not all, topical ophthalmic drugs used in our national health system have been collected, including information on the allergens available, and the concentration and vehicle advised for those that still remain unavailable.

Allergic Contact Dermatitis to Topical Ophthalmic Drugs: Review of Frequently Used Allergens in Spain

Allergic contact dermatitis induced by the use of ophthalmic topical drugs is one of the most common causes of eyelid dermatitis. The introduction of new formulations, both of active ingredients and excipients, and the lack of marketing in some of them, makes patch testing in patients whose source of contact are topical ophthalmic drugs truly challenging. Across this manuscript, most, if not all, topical ophthalmic drugs used in our national health system have been collected, including information on the allergens available, and the concentration and vehicle advised for those that still remain unavailable.

A Comprehensive Analysis of Immunoglobulin E Levels, Allergen-Specific Sensitivities, and Clinical Manifestations in Allergic Dermatological Conditions: A Multicenter Retrospective Study in China

Objective

To assess the correlations between Immunoglobulin E (IgE) levels, pruritus, and lesion severity in patients with eczema, atopic dermatitis, or urticaria.

Methods

A retrospective study was conducted and data of 814 patients who visited the dermatology or allergy clinics of multiple hospitals, from December 2019 to December 2021, were collected. Patients were divided into children group (<18 years, 325 cases), adult group (18-60 years, 435 cases), and older population group (>60 years, 54 cases) based on the age. Baseline information, pruritus severity, severity of skin lesions, total IgE level, and specific IgE level were recorded to analyze the complex relationship between them.

Results

The prevalence of allergic conjunctivitis and allergic rhinitis in the children group was significantly higher than that in the adult and older population group (P < 0.01 or P < 0.05). The positive rate of specific IgE in children group was significantly higher than that in the adult and older population group (P < 0.01). The IgE levels in children with moderate pruritus were significantly lower than those of severe pruritus (63.39vs 114.42 IU/mL, P < 0.05). The IgE levels in children with mild and moderate skin lesions were significantly lower than those in children with severe skin lesions (58.95 vs 72.88 vs 169.15 IU/mL, P < 0.001 or P < 0.01, respectively).

Conclusion

Relationships among age, severity of skin pruritus and lesions, and allergen-specific IgE response are complex and subtle, displaying dynamic patterns.

[DRESS syndrome induced by anti-TB drugs]

OBJETIVE

To describe the phenotype of DRESS syndrome induced by antituberculosis drugs.

METHODS

Descriptive study, withdrawn from the review of the records of patients with DRESS syndrome, identified in the interconsultation of the Department of Research in Immunogenetics and Allergy, of the Insti-tuto Nacional de Enfermedades Respiratorias (INER) Ismael Cosío Villegas, among 2014 and 2020. Frequency analysis was performed. The associations between biomarkers and latency are calculated with the χ2 test and log-rank, and the evaluation of the change in the biomarkers with the Wilcoxon test. The value of p < 0.05 is considered statistically significant. For data analysis, the SPSS v.21 program was obtained.

RESULTS

15 patients were identified; represented by 0.02% of total cases treated in the Department for so-meimmuno-allergic condition (15/7052); the main symptomatology were: rash (100%), eosinophilia (93%), fe-ver (80%), adenomegaly (60%), kidney damage (40%), liver damage (33%), and latency of 21 days. Liver damage was associated with prolonged latency (p = 0.02). After treatment, the total levels of eosinophils (p < 0.001) and liver and kidney biomarkers (p < 0.04) decreased. DRESS syndrome induced by antituberculosis drugs is not associated with the number of drugs prescribed or with the pattern of resistance of Mycobacterium tuberculosis.

CONCLUSIONS

DRESS syndrome induced by antituberculosis drugs is an atypical clinical reaction, similar to other types of DRESS syndrome that respond favorably to systemic corticosteroids.

Artificial Intelligence That Predicts Sensitizing Potential of Cosmetic Ingredients with Accuracy Comparable to Animal and In Vitro Tests-How Does the Infotechnomics Compare to Other "Omics" in the Cosmetics Safety Assessment?

The aim of the current study was to develop an in silico model to predict the sensitizing potential of cosmetic ingredients based on their physicochemical characteristics and to compare the predictions with historical animal data and results from "omics"-based in vitro studies. An in silico model was developed with the use of WEKA machine learning software fed with physicochemical and structural descriptors of haptens and trained with data from published epidemiological studies compiled into estimated odds ratio (eOR) and estimated attributable risk (eAR) indices. The outcome classification was compared to the results of animal studies and in vitro tests. Of all the models tested, the best results were obtained for the Naive Bayes classifier trained with 24 physicochemical descriptors and eAR, which yielded an accuracy of 86%, sensitivity of 80%, and specificity of 90%. This model was subsequently used to predict the sensitizing potential of 15 emerging and less-studied haptens, of which 7 were classified as sensitizers: cyclamen aldehyde, N,N-dimethylacrylamide, dimethylthiocarbamyl benzothiazole sulphide, geraniol hydroperoxide, isobornyl acrylate, neral, and prenyl caffeate. The best-performing model (NaiveBayes eAR, 24 parameters), along with an alternative model based on eOR (Random Comittee eOR, 17 parameters), are available for further tests by interested readers. In conclusion, the proposed infotechnomics approach allows for a prediction of the sensitizing potential of cosmetic ingredients (and possibly also other haptens) with accuracy comparable to historical animal tests and in vitro tests used nowadays. In silico models consume little resources, are free of ethical concerns, and can provide results for multiple chemicals almost instantly; therefore, the proposed approach seems useful in the safety assessment of cosmetics.

Patch testing: Uses, systems, risks/benefits, and its role in managing the patient with contact dermatitis

Patch testing is the gold standard diagnostic tool for cell-mediated type IV hypersensitivity reactions like allergic contact dermatitis. Sensitized individuals have primed antigen-specific T lymphocytes that cause a reaction when antigens are applied to the skin owing to prior sensitization. Patch testing can be used in the adult and pediatric populations, but it is contraindicated in patients with a known history of severe allergic reactions to suspected allergens, generalized active dermatitis, or extensive eczema. Patch test systems can be a comprehensive panel (70-80 allergens), but they can also be targeted and limited to a more common allergen series (35 allergens). The decision for allergen selection should be based on an accurate patient history, physical examination, and availability of allergens. Measurement and interpretation of the test results requires training and experience, as well as consideration of relevance and clinical history. Patch testing is generally considered safe with just a few known complications: excited skin syndrome, active sensitization, and rarely anaphylaxis or other cutaneous complications. Appropriately pretesting patient education can help to mitigate some of these complications. Based on patch testing results, patients should be educated regarding proper allergen avoidance measures to resolve symptoms of allergic contact dermatitis.

Contact Dermatitis: Classifications and Management

Contact dermatitis (CD) is a common inflammatory skin disease caused by exposure to contact allergens and irritants. It is also the most common reason of occupational dermatitis and contributes greatly to hand dermatitis and facial dermatitis. Besides the two major forms of contact dermatitis: allergic contact dermatitis and irritant contact dermatitis, other subtypes of CD have been recognized including immediate skin reactions, photoinduced contact dermatitis, systemic contact dermatitis, and non-eczematous contact dermatitis. CD is a great imitator which can mimic many kinds of skin diseases, such as atopic dermatitis, lichen planus, and angioedema. For the diagnosis of CD, a complete medical history, including occupational history, is very important. It can give a clue of CD and provide a list of suspected substances. Besides the well-known diagnostic test, patch testing, there are many other diagnostic tests can be used to help diagnosis of CD and identify the causative allergens, including photopatch test, skin tests for detecting of immediate contact reactions, serum allergen-specific IgE test, and qualitative and quantitative testing of allergen in the suspected materials patients exposed to and challenge test. Before the treatment, the suspected irritants or allergens should be avoided completely. This includes both the removal of the patient from the environment that contains those substances and the promotion of the metabolism and expulsion of the allergens that have been absorbed by the body. In addition, it is also important to restore the skin barrier and reduce skin inflammation through multiple treatments, such as emollients, topical corticosteroids, and antihistamines, as well as systemic corticosteroids and immunosuppressants. Early and appropriate treatments are important to prevent further deterioration and persistence of the skin condition.

Allergy Considerations in Implanted Neuromodulation Devices

OBJECTIVES

Allergic reactions are rare and poorly understood complications of neuromodulation device implantation. There are currently no guidelines for management of allergic reactions to these devices and their components. Here we review the published cases of allergic reactions to implanted neuromodulatory devices and leverage the experiences of other specialties that deal with similar complications to formulate recommendations for prevention and management.

MATERIALS AND METHODS

A review and assessment of the literature.

RESULTS

Allergic reactions to a number of implantable devices have been observed and published. In dentistry and orthopedics, metals such as nickel are the most frequent cause of allergic reactions. In interventional cardiology, where devices closely resemble neuromodulatory devices, titanium, silicone, and polyurethanes are the most common causes of allergic reactions. In neurosurgery, allergic reactions to implantable neuromodulatory devices are rare, and we summarize 13 cases published to date. Such allergic reactions generally present as local dermatitis, erythema, and pruritus, which can be difficult to distinguish from surgical site infection. In one published case, symptoms resolved with corticosteroid treatment, but all other cases required explantation. The successful reimplantation with a modified device was reported in some cases.

CONCLUSIONS

Patients should be screened for a personal history of contact allergy before implantation procedures. A multidisciplinary approach to suspected cases of postoperative allergic reactions involving collaboration between neurosurgeons and other implanting physicians, dermatologists or allergists, and device manufacturers is recommended. In cases where an allergic reaction is suspected, an infectious etiology should be ruled out first. Clinical suspicion can then be supported with the use of patch testing, interpreted by an experienced dermatologist or allergist. If patch testing supports an allergic etiology, the implanting physician and the device manufacturer can work together to modify the device for safe reimplantation.

Optical coherence tomography for patch test grading: A prospective study on its use for noninvasive diagnosis of allergic contact dermatitis

BACKGROUND

The diagnosis of allergic contact dermatitis should be confirmed by skin patch tests. Distinguishing between irritant and allergic reactions is sometimes difficult.

OBJECTIVES

To analyse the in vivo morphological changes in patch test reactions compared to healthy skin, and to detect subclinical changes in doubtful reactions using optical coherence tomography (OCT). To develop an OCT-based algorithm to support patch-test grading.

METHODS

One hundred twenty-nine skin patch-test areas were scanned with OCT to evaluate the following features: architectural and vascular morphology, epidermal thickness, optical attenuation coefficient (AC), and blood flow at 0.1, 0.2, and 0.35 mm depth.

RESULTS

Most common OCT features of acute contact allergic reactions in patch tests were spongiosis with microvesicles (94.8%), macrovesicles (60.3%), and coalescing vesicles (46.6%), the latter useful in differentiating acute allergic from irritant dermatitis (P-value < .05). Objective quantitative parameters correlated well with the severity grade: epidermal thickness due to spongiosis, AC (P-value < .05) and blood flow at 0.2 and 0.35 mm (P-value < .01).

CONCLUSIONS

OCT as a noninvasive diagnostic tool, established for skin cancer diagnosis, is useful for evaluating contact allergic patch-test reactions. Not only morphological but also objective features such as blood flow and AC correlate with the reaction severity. Further studies are needed to explore the differences in irritant and allergic contact dermatitis.

Medical devices in allergy practice

Medical devices provide people with some health benefits in terms of diagnosis, prevention, treatment, and monitoring of disease processes. Different medical specialties use varieties of medical devices more or less specific for them. Allergology is an interdisciplinary field of medical science and teaches that allergic reactions are of systemic nature but can express themselves at the level of different organs across the life cycle of an individual. Subsequently, medical devices used in allergology could be regarded as: 1) general, servicing the integral diagnostic and management principles and features of allergology, and 2) organ specific, which are shared by organ specific disciplines like pulmonology, otorhinolaryngology, dermatology, and others. The present position paper of the World Allergy Organization (WAO) is meant to be the first integral document providing structured information on medical devices in allergology used in daily routine but also needed for sophisticated diagnostic purposes and modern disease management. It is supposed to contribute to the transformation of the health care system into integrated care pathways for interrelated comorbidities.

Role of in vivo and in vitro Tests in the Diagnosis of Severe Cutaneous Adverse Reactions (SCAR) to Drug

Severe cutaneous adverse reactions (SCAR) are life-threatening conditions including acute generalized exanthematous pustulosis (AGEP), Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN) and drug reaction with eosinophilia and systemic symptoms (DRESS). Diagnosis of causative underlying drug hypersensitivity (DH) is mandatory due to the high morbidity and mortality upon re-exposure with the incriminated drug. If an underlying DH is suspected, in vivo test, including patch tests (PTs), delayed-reading intradermal tests (IDTs) and in vitro tests can be performed in selected patients for which the suspected culprit drug is mandatory, or in order to find a safe alternative treatment. Positivity of in vivo and in vitro tests in SCAR to drug varies depending on the type of reaction and the incriminated drugs. Due to the severe nature of these reactions, drug provocation test (DPT) is highly contraindicated in patients who experienced SCAR. Thus, sensitivity is based on positive test results in patients with a suggestive clinical history. Patch tests still remain the first-line diagnostic tests in the majority of patients with SCAR, followed, in case of negative results, by delayed-reading IDTs, with the exception of patients with bullous diseases where IDTs are still contra-indicated. In vitro tests have shown promising results in the diagnosis of SCAR to drug. Positivity is particularly high when the lymphocyte transformation test (LTT) is combined with cytokines and cytotoxic markers measurement (cyto-LTT), but this still has to be confirmed with larger studies. Due to the rarity of SCAR, large multi-center collaborative studies are needed to better study the sensitivity and specificity of in vivo and in vitro tests.